Secondary Hemophagocytic lymphohistiocytosis in an immunocompetent adult: a case report distinguishing sarcoidosis from histoplasmosis.

Distinguishing between histoplasmosis and sarcoidosis can be challenging as both can present with non-specific clinical findings. We present a 73-year-old immunocompetent Caucasian male who was recently diagnosed with sarcoidosis via left upper lobe biopsy who presented with lethargy and poor oral intake. The patient was found to have fever, splenomegaly, pancytopenia, hypofibrinogenemia, and elevated inflammatory markers. After bone marrow biopsy, he was diagnosed with disseminated histoplasmosis and secondary hemophagocytic lymphohistiocytosis (HLH). The patient was treated with liposomal amphotericin B and a dexamethasone taper followed by itraconazole for 1 year. After the patient was found to have disseminated histoplasmosis, his original diagnosis of sarcoidosis was reconsidered. Disseminated histoplasmosis is a rare cause of secondary HLH in an immunocompetent adult. This case highlights the difficulties distinguishing between histoplasmosis and other causes of granulomatous disease and identifies histoplasmosis as a rare cause of HLH.